As computers increase in performance and capability, the cooling of the electronic modules contained therein becomes more difficult. Cooling of the electronic modules is necessary for high speed operation of the electronics and additionally for sustained reliable operation of the electronics. The cooler the modules are maintained, the higher the operating speeds and reliability obtainable during such operations. As the temperature of the electronic modules increases device switching times accordingly increase and slow the operation of the circuits contained in these modules as well as thermally stress the modules to the point where reliability may suffer. In cooling the electronic modules within the computer it is desirable, if not absolutely necessary, to maintain uniformity of temperature so that interconnected electronic modules may operate at substantially the same speed and thereby not create operational mismatches which result from thermal mismatches.
Uniformity of cooling of the electronic modules is difficult to obtain. Non-uniformity problems may result from the fact that as a cooling fluid flows from one location to another over a surface, thereby absorbing the heat from that surface, the temperature of the cooling fluid inherently will rise. As the temperature of the cooling fluid rises, the differential temperature diminishes between the cooling fluid and the surface over which it flows. With a diminished differential temperature, the heat transfer from the hot surface to the cooling fluid is reduced, thereby resulting in warm or hot spots near the end of the cooling fluid flow path. Moreover, cooling efficiency degrades substantially with longer flow paths which only exacerbates the problem of hot spots at the warm end of the flow path. Hot spots occur within the cold plate which in turn will result in inadequate cooling of the electronic modules and inherently will create substantial temperature differentials between electrically interconnected electronic modules; accordingly, with such thermal mismatches, mismatches in performance may occur.
Past efforts to cool a plate by bathing one entire surface of the plate with a cooling fluid resulted in uncontrolled flow of the coolant; where the flow is not uniform over the surface of the plate, temperature inequality occurs with warm or hot spots developing in areas of inadequate coolant flow.
Further where only a single planar surface is cooled by the flow of a cooling fluid, the heat transfer to the cooling fluid across this single surface may be insufficient to maintain the electronic modules at desired or optimal temperatures.